Rhythm's Setmelanotide Phase 2 Data in PWS at ENDO 2026

On June 13, 2026, Rhythm Pharmaceuticals announced positive interim six-month data from its exploratory Phase 2 trial of setmelanotide in 18 patients with Prader-Willi syndrome (PWS). The trial demonstrated a mean BMI reduction of 3.06% across all patients (n=17). Specifically, adult patients saw a 3.11% mean reduction, while pediatric patients achieved a mean BMI z-score reduction of 0.35. Clinically meaningful improvements were also observed in hyperphagia scores, with 80% of patients with moderate-to-severe baseline hyperphagia achieving a reduction of 7 points or more on the HQ-CT. Additionally, 10 of 15 patients with high baseline anxiety scores showed meaningful improvements. Safety remained consistent with setmelanotide's established profile. Furthermore, Rhythm presented long-term data at ENDO 2026 for Acquired Hypothalamic Obesity (HO), showing an 18.9% mean BMI reduction over 2.5 years with setmelanotide and significant BMI reductions with oral bivamelagon after one year. Real-world data for Bardet-Biedl syndrome (BBS) indicated that 62% of adults achieved ≥10% body weight loss after 12 months of setmelanotide treatment. The company plans to advance setmelanotide into Phase 3 trials for PWS based on these results.